Yahoo! is offering its instant messaging service without the need to download and install a separate application.

The change allows people working for companies which stop staff downloading and installing applications to use the service. It will also make the service usable for people in internet cafes that don't already have the standalone messenger software installed.

The messenger window allows you to tab, so you can run several conversations from one window. There is a searchable archive of past conversations and you can also add contacts from Windows Messenger.

The service is launching in Brazil, India (in English), Malaysia (English), the Philippines (English), Vietnam, and the US (in English and Chinese versions), with other countries and languages to follow.